THE STOPPED DIAPASON.

Why do we begin by making a set of wooden pipes?

For two reasons. First, because they will afford a trial of patience, and involve a great deal of good joinery. Second, because until they are made, or, at any rate, until we know their precise dimensions, we cannot plot out with accuracy the very important sound-board, which is to carry them and the other pipes which are to follow. Either of these reasons is, to our mind, sufficient, apart from the other; and we strongly recommend the young beginner to set himself resolutely to the manufacture of the complete set of wooden pipes belonging to the commonest of all organ-stops, the Stopped Diapason, before taking any step in the direction of the machinery or apparatus which is to waken them into harmonious vibrations.

Our explanations will be much assisted here if we introduce a few definitions of terms in constant use. The pipes which we are about to make will give notes, when tuned, which are familiarly designated by certain names. Thus, the lowest note on the manual or key-board of modern organs is called Double C (printed CC). The note one octave above this is Tenor C; the octave of Tenor C is Middle C; and above this, again, we have Treble C (often called Foot C) and C in Alto. Some of the other notes of the scale, in a similar way, have convenient names. Thus, the first F in the bass is Double F, or FF; the next F, the F of the Tenor octave, is often called Clef F, as the Bass, or F Clef, stands upon this line in music; its sharp is FF sharp; but then we come at once to a single G, and this note is often called Gamut G. The octave above this note is called Fiddle G, as it sounds the same note as the fourth string of the violin. The note B, we may add, throughout the organ, is understood to mean B flat; the semitone above this is indicated by the musical symbol the Natural (?).

We have not quite done with this. There is another way of referring to pipes, and to complete sets of pipes, which is in familiar use, and is part of the mother-tongue of the organ-builder. We have said that Treble C is often called Foot C. This is because the ordinary open pipe of that note (speaking now quite inexactly, and without precision), is 1 foot in length. In a similar way, CC is 8-foot C, or the 8-foot note, because the open pipe is 8 feet in length, speaking roundly or roughly. Tenor C is 4-foot C; Middle C, 2-foot C.

It will be easily understood that these convenient designations are retained, even though the construction of the pipes may render them strictly inapplicable. Thus, the lowest note of our first stop will still be 8-foot C, though, as we shall soon see, the stopping of the wooden tube enables us to reduce the actual length by one-half. Our CC will still be of 8-feet pitch, or tone, and by no means becomes a 4-foot C, because its actual measurement, when completed, will not exceed 4 feet in total length.

One step further. The theoretical length of the lowest note is not only used to designate that note and the pipes which belong to that note, but is extended to the designation of the whole set of pipes of which it is the lowest or longest. This whole set of pipes is called familiarly a Stop; thus we have at once the ready terms, 8-feet stops, 16-feet stops, 4-feet stops, 2-feet stops, &c.; and it will be understood that by an 8-feet stop, we mean a set of pipes yielding the common or ordinary pitch of the pianoforte, or of the human voice; while a 4-feet stop, when the very same keys are pressed down, will yield notes one octave higher than this ordinary or standard pitch; the 2-feet stop, notes two octaves higher; the 16-feet stop, notes one octave lower, or deeper. And if all these four stops are played at the same time, (tuning and other manipulations being now assumed), an effect will be produced highly agreeable to the ear, and vastly superior to that which would result from the mere multiplication of 8-feet stops only.

Our little organ of five stops, when completed, will probably be described with correctness if it is said to contain two 8-feet stops, two 4-feet stops, and one 2-foot stop: a ready and conventional way of speaking, we repeat yet once more, since the instrument will contain no open pipe 8 feet in length, and since, of the 4-feet stops, one will be only of 4-feet tone, or pitch, while even the 2-feet stop, for reasons which will be abundantly made clear, may possibly have no 2-feet pipe.

Some pains have been taken to explain all this, because we have met with young workmen whose comprehension of such rudimentary matters was far from complete, and who were misled by the fanciful and wholly unimportant names engraved upon the knobs which govern the stops, e.g. "Flute," "Dulciana," &c. If we have any such young beginners among our present readers, they will see that the names are quite of secondary concern, and that the essential thing is to have a clear understanding of the pitch of each stop, as represented by the length of the pipe, actual or virtual, corresponding to the lowest note of the manual.

And now we proceed to our work. What we have to do is to make fifty-four pipes, extending from CC to F in alto, and of the form or sort known in England as Stopped Diapason. One of these pipes, let us suppose Tenor C, is shown in Fig. 1. a is a block of mahogany or oak, or of some other wood faced with mahogany or oak, and about 3 inches in length. It has a throat or deep depression across it, formed by taking out the wood between two saw-cuts, or by boring adjacent holes with a centre-bit. b is a stopper, made of any wood, the exact size of the block, or a trifle less, to allow for a leather covering, and fashioned at top into a knob, or turned in the lathe, for convenient handling by the tuner. c is the pipe when put together by gluing three boards, namely, the back and the two sides, to the block, and one, namely the front board, to the edges of the sides. This fourth board is about 3 inches shorter than the others, and has a lip formed on its lower edge by bevelling the wood with a sharp chisel. d is a cap, 3 inches long, and as wide as the block with the side boards attached; it is hollowed in a wedge-shaped form as shown in the figure. e is a foot, turned in the lathe, bored from end to end, and 5 or 6 inches in length. f is the completed pipe, with the stopper inserted, the cap put on, and the foot in its place.

We have to make fifty-four such pipes, each of the dimensions proper for the production of its own note, deep in the bass or shrill in the treble.

It is quite clear that we must not work by "rule of thumb," but understand well what we are about from the very first, if we do not wish to cut our wood to waste and cover ourselves with mortification.

Begin thus. Take a sheet of stout paper, and on it, with rule and compasses, draw a scale showing all the requisite measurements.

Here we must be a little arbitrary, and lay down the law without giving lengthy reasons for our ruling. Stopped pipes are half the length of open pipes yielding the same notes. Our CC pipe will therefore be 4 feet long. The four C's of the ascending scale are the halves of each other. Therefore Tenor C will be 2 feet, Middle C 1 foot, Treble C 6 inches, and C in alto 3 inches, in length. The word nearly, or about, must be understood as prefixed in every case to our measurements. Accordingly, the lengths of all the pipes in the stop will be easily obtained by drawing a vertical line 1 foot in length on the paper, and dividing it into twelve equal parts. At the bottom, write Tenor C, 2 feet; at the top, Middle C, 1 foot. Then the length of each of the eleven pipes intervening between these extremes will be at once obtained by easy measurement. By doubling these lengths we shall obtain those of the bass, or 8-feet octave. By halving them, those of the middle octave. By dividing them by four, we get those of the treble octave.

Note well that these rough and approximate lengths are speaking lengths of the wooden tubes, or, in other words, of the column of air within them, measured from the top of the block to the under side of the stopper. Hence, in cutting out the boards, the length of the block—about 3 inches, or less in small pipes—must be added to three of them, and an inch or more allowed to all four of them to give good room for the stopper.

But we are not yet in a position to cut out the boards.

It might be thought that as we get the lengths by the easy arithmetical process described above, so with equal ease shall we get the widths and depths of the blocks. The pipes are not square, but are deeper than they are wide, in the proportion of about 5 to 4. It might be thought that if the block of Tenor C be 2 inches wide and 2½ inches deep, then the block of Middle C will be 1 inch by 1¼ inches; the block of Foot C ½ inch by ?, and so on. This is not so. These treble pipes would be quite unreasonably small, and would give weak and thin sounds, while the bass octave, commencing with a block 4 inches by 5 inches, would be needlessly large for a chamber organ. Without wasting words upon a matter which is really very simple, let us say at once that we shall adopt for our Stopped Diapason a scale commencing with a CC block 3¼ inches wide and 4 inches deep, and that the block of Tenor C will be 2? inches wide and 2? deep. Thus the half of the width and depth of the CC block will not be reached until the eighteenth note above it, instead of the thirteenth, and in the higher parts of the scale the diminution in the sizes of the blocks may be yet more gradual.

A glance at Fig. 2 will enable our readers to draw scales for themselves for the Stopped Diapason, and for other wooden stops which may follow it, from a few given data, and to suit circumstances. A minute or Chinese accuracy is not requisite. The vertical line of any convenient length being drawn upon the paper, the width and depth of the CC block are measured off upon a horizontal line drawn at its lower extremity. Eighteen divisions being marked upon the vertical line, the half-width and half-depth of the CC block are measured upon another horizontal line drawn at the eighteenth mark. These points being joined by straight lines, and horizontal lines being drawn at each of the marks parallel to the others, we shall have the widths and depths of the blocks of all the pipes from CC to Clef F inclusive, viz. eighteen blocks. The next eighteen blocks will be sized in a precisely similar manner, and as three times eighteen is equal to fifty-four, the whole stop may be divided into three sections of eighteen pipes in each section, and it may be for our convenience to make one section at a time.

There are two methods of working together the block and the four boards which form the pipe. We will give them both, and decide between them.

First method. Cut out the board for the back, and dress it carefully to the exact width of the block. Glue the block to the lower extremity, and when the glue is dry dress up all perfectly flush. Cut out the side boards as wide as the depth of the block with the thickness of the back board added to it. Glue them to the sides of the block and to the edges of the backboard, obtaining a perfectly close joint by using wooden clamps and wedges as in gluing up a violin, or by other obvious contrivances. When the glue is dry dress up the front edges flush with the block, and glue on the front board, which will be cut out as wide as the block together with the thicknesses of the side boards. The front board must overlap the upper edge of the block by about ? inch or more. If all this is carefully done according to the rules of good joinery the result should be a neat and strong pipe, truly rectangular at its upper or open extremity. Brads or sprigs are not to be thought of in pipe-making, unless, indeed, in the very exceptional case of organs intended for tropical climates.

Second method. Cut out first the two side boards the width of the depth of the block, and glue them to it. Dress the edges flush with the block, and glue on at once the back and front boards, obtaining irreproachable joints as before, and taking infinite care that the upper extremities of the side boards do not approach each other. In making our smaller pipes (say from Middle C upwards), we are in the habit of straining whip-cord or stout hempen string round them, winding it first upon a loose pipe-foot or smooth tool-handle to avoid cutting the hands; and we ensure a correct aperture at the top by placing within it a thin slice cut from the block itself, or by introducing the stopper if it has been already prepared of the same size as the block. The notches made by the string upon the edges of the soft pine-wood are easily removed when the finished pipe is dressed over with a fine plane.

We have no difficulty in giving our decision in favour of the second plan, which avoids the four tedious dryings of the glue, and which admits more readily of pressure being applied to the freshly glued joints. But in making open pipes, which have not to bear the driving-in of a stopper, there is much to recommend the first method.

This point being settled, we may cut out the side boards and prepare the blocks for one of our divisions, let us say the middle section, from Clef F sharp to the natural below Foot C. Blocks of this moderate size will be best made by taking a piece of wood of suitable character, long enough for six or more, and by dressing it down as each block is cut off, making careful and constant use of the gauge, the square, and the callipers. We like to form the throat with a centre-bit after the pipe is put together. The thirty-six boards will be glued to the eighteen blocks, and while the glue is drying we can prepare the backs and fronts. The bevelled lip of the latter will be left uncut until all the pipes have been glued up and dressed over, and the top edges nicely cleaned off and made true. But as there will be, doubtless, a most pardonable anxiety to hear the sound of one pipe, we will here explain that the height of the mouth of each pipe must be equal to one-third of its width; thus the mouth of the pipe measuring one inch and a half across the block (A in our scale) will be ½ inch in height. In measuring the height of the mouths, a pair of proportional compasses with sliding centre, or common dividers set to thirds, fourths, and fifths, will be useful if not necessary. The slope of the bevel is not of great importance. Cut it with a sharp chisel, taking care not to injure the block, and leave the lower edge or lip rather blunt. A sharp and pointed knife may be employed in cutting the lip truly, guided by the square. The use of fine glass-paper is permissible here to smooth all these parts nicely.

The throat having been formed in the face of the block, about 1 inch from its lower end, bore the foot-hole in the bottom of the block clear into the throat, beginning with a small borer, and enlarging the hole cautiously, as rough and hasty proceedings might split the block at this point, especially in the case of small pipes.

Prepare the cap from a suitable bit of mahogany, oak, or other close-grained wood, and hollow out the back of it with a chisel as shown in d, Fig. 1. Form the flue or wind-way through which the air is to pass to the lip by filing away the edge left at the top of the wedge-shaped hollow, trying your work by placing the cap against the side of the pipe or any other flat surface. The flue must not be wider than 1/16 inch at Tenor C, and must be reduced as we ascend the scale until it will hardly admit a slip of thin paper. It will not be so much as ? inch wide even at CC.

Perhaps the stopper has been already prepared of the same size as the block, and has been formed into a knob at top, or turned in the lathe, or, in the case of the larger pipes, fitted with a turned handle glued into a hole bored for its reception. Dress off the angles of the stopper in order to allow room for the soft white leather with which it is covered to fold itself in the corners of the pipe. We generally rasp our stoppers, leaving them rough that the leather may cling to the stopper and not to the pipe. The leather cannot be too thin if it is soft, and if the stopper fits closely. Rub the interior of the top of the pipe with a bit of tallow-candle, and introduce the stopper cautiously. It should slide within the pipe at once easily and with accurate fit, and if your joinery has been good there should be no fear of splitting the pipe or of opening the joints.

The cap when finally fitted will have its upper edge about ? inch below the upper edge of the block. On applying it in this position, holding it there with your fingers, or tying it on with string, and blowing gently into the foot-hole, you will have a pleasant fluty musical note. Probably a little chirp or whistle will be heard before the note comes on. The removal of this defect belongs to the important operation called voicing, of which we shall treat hereafter.

We have cut our boards from the half-inch pine, but as we rise in the scale much thinner stuff will be used. It is well to foresee this in laying in our materials. Red cedar, often used by cabinetmakers for the inside of drawers and wardrobes, makes very pretty pipes, holds the glue well, and has an agreeable odour in working. Harder woods, notably oak, were often used by the old builders. Pear-tree commends itself much in German workshops.

The four or five lowest pipes (CC to EE, or higher) should be of stouter stuff than half-inch, say five-eighths or even three-quarters. The caps of these large pipes will not be glued on but fixed with three screws, and we may modify a previous remark by admitting that in the case of these larger pipes the use of nails is legitimate.

Of the pipe-feet we shall speak when we come to the business of planning the rack-board with its holes for their reception.

We must not close this chapter without giving some further explanations on the subject of pipe-making.

Large pipes, both open and stopped, may be advantageously made with languids instead of blocks. Fig. 3 shows the section of a pipe so made. The block is replaced by two pieces of suitable wood, a a, let into the side boards with plenty of glue. The glue should also be allowed to run freely into the angles and corners of the throat when the back board is fitted. Pipes made in this way are a little lighter than those with blocks.

The stoppers of the smaller pipes, say from Fiddle G or Middle C to top, are often bored with a hole passing clear through the wood and leather, and burnt smooth with an iron. After what has been said of the necessity of securing a good fit for the stopper, it might be thought that this hole would ruin the pipe. Curiously enough it is not so, but imparts a slight increase of fulness to the tone. The holes must not be large, ¼ inch at Middle C will be sufficient. Note well that pipes with perforated stoppers must be a trifle longer, say 1 inch in 12, than those completely closed. Thus the pipe for C sharp must be as long as the fully stopped C pipe.

Wooden pipes are also made with inverted mouths, that is to say, the bevelled lip is formed on the inside instead of on the outside of the front board. In this case the bevel is cut and the mouth measured and formed before the pipe is put together, and the front board will be of the same length as the others, and will be glued like them to the block. The throat is cut through the board into the block, and the cap will project beyond the level of the board. All this is shown in Fig. 4.

We have a very charming Stopped Diapason made in this way, and with perforated stoppers, in one of our organs. It is of red cedar from Middle C to top; the lower part is of pine and of the ordinary construction. The mouths are in the proportion of two-sevenths of the width of each pipe. Inverted mouths are well suited, also, to the Clarabella and Hohl FlÖte, two kindred stops which sometimes take the place of the Stopped Diapason in its upper octaves. The pipes are open, and have a hollow penetrating tone; Middle C is 2 feet long, and its block may be of the same size as that of the same note in our scale, namely, about 1? by 1¾. The mouth about 2/7 of the width. These open pipes are tuned by means of shades, which are pieces of pipe metal let into a saw-cut made in the top edge of the back board. The shade must be as wide as the pipe, and ½ inch longer than its depth. The pipe is flattened by bending the shade over the open top, sharpened by raising it.

The German stop, the Doppel-flÖte, which has two mouths opposite to each other, and of course two caps for each pipe, is seldom or never heard in this country. A few pipes which we have made as experiments hardly seem to repay us for the additional trouble and labour.

Trouble and labour were of little account, apparently, in the old days of English organ-building two centuries ago, if we may judge from the really marvellous specimens of patient pipe-making in wood which have come down to us. We ourselves have seen and played organs of exquisite sweetness and beauty by old Bernhard Schmidt (1660-1708), containing four or five stops in which every pipe was of oak, even up to the top note of a Fifteenth of 2 feet. Such an organ, built by Loosemore, 1664, the builder of the cathedral organ, is preserved, we believe, at Exeter. It has six stops, including a Twelfth, all made of wood. Modern life is too hasty and impetuous for such efforts. If any of our readers, however, should set themselves the task of making very small pipes in wood, we advise them to form the block and foot from one piece, and to follow the first method (see p. 18) in putting the minute contrivance together.